U.S. Customs and Border Protection officers at Los Angeles International Airport in July. The airport was the site of panicked mobs Sunday night which, as Walter Shapiro writes, were probably related to fear-based campaign themes from this year's presidential election. (David McNew/Getty Images file photo)

Sunday night, in case you missed it, Los Angeles International Airport was closed because of a panic attack. The threat came not from terrorism or a crazed gunman, but rather from wild, incoherent passenger hysteria.

The incident may have been triggered by random loud noises or possibly a man in a Zorro costume with a plastic sword. But it quickly morphed into rumors of an active shooter as frightened passengers in three terminals raced out through TSA checkpoints and burst through restricted doors onto the tarmac.

Douglas Lee, a passenger from Albuquerque, New Mexico, told The Associated Press of his fear of being trampled. "You can imagine hundreds of adults trying to get through an exit door," he said. Los Angeles Mayor Eric Garcetti likened the uproar to "a game of telephone" in which each rumor became wilder than the last.

It might be tempting to dismiss the chaos at LAX as a minor summer squall brought on by the stress of air travel and memories of a 2013 shooting at the airport. But just two weeks ago, Kennedy International Airport in New York was the scene of an even more harrowing outbreak of irrational passenger panic with dangerous stampedes for the exits and security guards sobbing that they didn't want to die.

In a memorable account in New York magazine, David Wallace-Wells, who had been a passenger at JFK, wrote, "Panic turned us all into animals. And the airport, designed to contain and channel people, had never felt more like a slaughterhouse corral."

When the histories of this ugly campaign year are written, I hope that some attention is devoted to analyzing the Great Fear that was reflected in these August nervous breakdowns at two of the nation's busiest airports.

Yes, of course, there has been skittishness at airports since 9/11 and the terrorist tragedies in Orlando and San Bernardino have reminded us of the continuing danger from ISIS acolytes. Mass murder, unrelated to terrorism, has also brought with it a sad-eyed sequence of the funerals of the innocent.

But in his New York magazine piece, Wallace-Wells captured the weirdness of what went on at JFK airport. He shuddered "that an institution whose size and location and budget should make it a fortress, in a country that has spent 15 year focused compulsively on securing its airports … could be transformed into a scene of utter bedlam … by the whisper of a threat."

For reasons beyond politics, America seems more panicky than at any time since the frightened months after the twin towers were toppled.

Angry speeches by Donald Trump and anti-immigrant screeds on alt-right websites didn't set off the stampeding frenzy at JFK and LAX. Nor did Barack Obama's foreign policy, the death of the American Dream or the lack of gun control cause this outbreak of the “Fear Factor.”

Maybe as al-Qaida has given way to ISIS, as terrorist attacks and maniacal shootings blur into each other, Americans have finally begun to confront the reality that they will never be 100 percent secure no matter who is in the White House or what policies are adopted.

Of course, there is a longing to go back to the days when terrorist incidents only happened in far-off lands and one could stroll through airports without worrying about security lines and being yelled at for violating TSA protocol. But, alas, those days have gone the way of milkmen delivering door-to-door and the Beatles on Ed Sullivan.

Maybe social media (that all-purpose explanation for everything from real estate prices to teenage acne) plays a role in making everything personal. A terrorist bombing at the Brussels airport feels much closer than a similar tragedy might have, say, twenty years ago. If we are all connected through Facebook and Twitter, then we are always just a few connections away from the victims of horrific events.

But perhaps the simplest explanation is that we have all grown weary of appearing stoic. There was a sense of personal bravery that flowed through the culture in the weeks and months after the Sept. 11 attacks.

It was a time when Americans embraced the rituals of everyday life — going to the movies, shopping malls and football games. It was a time when, as the cliche went, we had to carry on as if everything were normal or "else the terrorists will win."

Maybe 15 years after 9/11, we have come to feel as depleted as the British did in 1945 after they won the war. Maybe we have reached the point where it is no longer possible to "Keep Calm and Carry On."

I wish there were a simple glib explanation for why unreasoning fear created panicked mobs at two major airports in the same month. But I refuse to believe that this is just an odd coincidence unconnected to the most depressing presidential election in modern memory.

To quote the legendary comic strip Pogo, "We have met the enemy and he is us."

Roll Call columnist Walter Shapiro is a veteran of Politics Daily, USA Today, Time, Newsweek and the Washington Post. His book on his con-man great-uncle was just published: "Hustling Hitler: The Jewish Vaudevillian Who Fooled the Fuhrer." Follow him on Twitter @MrWalterShapiro.